EP0605825B1 - Thermoplastic plastics moulding matter, process of manufacture and moulding made therefrom - Google Patents

Abstract

After removing coarse fragments of glass and metal splinters from the grinding stock from motor vehicle rear light and indicator light units, it is possible to obtain from said stock a high-grade moulding composition comprising 50-65% PMMA, 25-40% ABS and 1-20% PC for the production of new rear-light and indicator-light housings. The constituents which melt at over 250@C and are longer than 0.2mm, if desired longer than 0.04mm, are separated off by melt filtration, thereby considerably improving the service properties.

Description

The invention relates to a thermoplastic molding compound from reconditioned motor vehicle rear and - Direction indicators, a process for their manufacture and from them generated moldings. The invention serves the Reuse of the used or unusable Lights contained plastic.

The reuse of materials wins - promoted by legal requirements and obligations - increasing economical meaning. In the course of a possible statutory obligation to take back retired items Motor vehicles have the task of being next to the steel Main component also other materials contained therein, including the plastic content, to be recycled. As single-use plastics are easily recyclable, provided they consist of end-of-life vehicles with reasonable dismantling effort recover without mixing with foreign materials. Are in appearance and technical characteristics recovered plastics of the appropriate new goods in inferior to the rule. On the one hand, this is due to the consequences of long-term use, with pollution, Weathering, oxidation and damage from light, heat and corrosive agents, on the other hand on the the corresponding improvement achieved in the meantime Plastic grades.

For these reasons, a real material cycle is at to which the plastic is fed to the same application, from which it was recovered, hardly possible in practice.

Plastic recycling is better through the picture a descending cascade, in which the Property level of the reused plastic is lower than the level of previous use. The aim of the invention is that "Recycling cascade" as flat as possible design, i.e. the least possible loss of quality to achieve when reused.

To the plastic parts from motor vehicles that for a Recycling also include the stern and Direction indicators. They usually contain one translucent, possibly colored cover Polymethyl methacrylate (PMMA) and a welded to it ABS plastic housing. In addition, lamp sockets, Incandescent lamps, electrical cables and fasteners Metal is often so firmly attached to the plastic body that a complete breakdown of technical and economic reasons. Only Rubber seals to seal the taillights and turn signals in leave the corresponding installation openings in the body remove yourself by hand if necessary.

Procedures are already being developed to dismantle full rear and turn signal lights for reuse prepare. They are crushed overall and that Regrind by magnetic separators, vibrating troughs, wind sifters and similar devices as much as possible different materials separated. This separation remains always imperfect, so that with broken glass, metal chips, Cable remnants, rubber particles, etc. in which predominantly from Plastic existing regrind is to be expected. Furthermore the remains of aluminum remain in the regrind existing mirror coating of Plastic reflectors.

The plastic that can be recovered from the rear and turn signal lights has so far only been available as a mixed plastic for the Manufacture of low-quality molded parts, for example for park benches, noise barriers, coil formers and the like Another physical and material recycling after such uses is hardly considered, so that Plastic after its second use from the Recycling cycle would be eliminated.

50 - 65 Gew.-% Polymethylmethacrylat (PMMA)

25 - 40 Gew.-% schlagzähe ABS-Kunststoffe

1 - 20 Gew.-% Polycarbonat-Kunststoffe (PC)

Analyzes of the cleaned regrind have shown the following average composition for the plastic content:

50-65% by weight polymethyl methacrylate (PMMA)

25 - 40% by weight impact-resistant ABS plastics

1 - 20% by weight polycarbonate plastics (PC)

DE-A 40 13 700 describes the suitability of thermoplastic Plastics of the same composition for the Manufacture of high quality technical molded parts for the Vehicle construction, for example parts of lamp housings, known. Attention is drawn to the possibility some or all of such plastics Assemble recycling components. The components fall in part already as mixtures, for example of ABS and PC, when recycling waste. The property values are those made of appropriate new plastic are practical equal. However, this only applies to the recycling of Production waste that is inevitable in manufacturing of vehicle tail lights and turn signals. This Waste is usually not made with foreign materials, such as Metals or glass, contaminated because of the reject parts not yet ready for installation with lamp holders, incandescent lamps, Connection cables, fasteners and the like. equipped were. They represent a pure plastic waste, the technical characteristics to those of the corresponding new goods not inferior.

On the other hand, complete rear and turn signals from Used vehicles collected, must be from the above Reasons with a significant deterioration of the Property image can be expected.

The invention has for its object the tail and Indicator lights of motor vehicles made of recyclable plastic to ensure the highest possible reuse. The ideal of the material cycle would come proportionately close when the plastic is made from reused tail and Flashing lights at least for the production of the non-transparent Parts of such lights can be reused could.

The prerequisites for high-quality reuse are correspondingly high technical property values, in particular a Vicat softening temperature of at least 102 ° C, a Tensile strength of at least 50 MPa or an elongation at break of at least 3%. These values are for the production of Sufficient housing parts for rear and direction indicators.

50 - 65 Gew.-% Polymethylmethacrylat oder Copolymerisate des Methylmethacrylats mit 1 bis 20 Gew.-% an damit copolymerisierbaren äthylenisch ungesättigtes, radikalisch polymerisierbares Monomeren, insbesondere niederen Alkylacrylaten,

25 - 40 Gew.-% schlagzähe Kunststoffe auf der Basis von Acrylnitril, Butadien und Styrol (ABS),

1 - 20 Gew.-% Polycarbonat-Kunststoffe (PC)

mit den oben angegebenen Eigenschaften gewinnen läßt, die überwiegend oder ganz aus wiederverwendeten Kfz-Rück- und Blinkleuchten besteht.It has been found that a thermoplastic molding compound of the composition:

50-65% by weight of polymethyl methacrylate or copolymers of methyl methacrylate with 1 to 20% by weight of ethylenically unsaturated, free-radically polymerizable monomer copolymerizable therewith, in particular lower alkyl acrylates,

25 - 40% by weight impact-resistant plastics based on acrylonitrile, butadiene and styrene (ABS),

1 - 20% by weight polycarbonate plastics (PC)

can win with the properties specified above, which consists predominantly or entirely of reused automotive rear and turn signals.

The ground material pre-cleaned in the manner described results in thermoplastic processing not yet required properties. On injection molded Test specimens were tensile strength of 47 - 48 MPa and an elongation at break of 2.2% was measured. Use as Technical molding compounds are mainly malfunctions in the Flow processes in extrusion and injection molding tools opposite.

Characteristic of the recovered from rear and indicator lights thermoplastic molding compositions is a content of particulate constituents, which are not fusible at processing temperatures up to 250 ^o C. They make up a share of 5 to 10% by weight in the pre-cleaned regrind. By reducing this proportion to less than 5% by weight, in particular to 1 to 4% by weight, the property level can be increased in such a way that it can be recycled industrially to form sophisticated moldings. The size of the infusible particles contained plays a role in the properties of the molding compound. If it is less than 0.2 mm, measured as the mesh size of a sieve or filter used to filter the melt, trouble-free processing is possible on conventional injection molding and extrusion machines. Reducing the particle size to less than 0.1 mm brings with it an improvement in the surface quality of the injection molded parts produced. Melt filtration at a sieve mesh size of 0.04 mm also separates gel-like elastic particles, which can come from rubber seals, which otherwise lead to streaking during processing due to thermal decomposition. The external appearance of the plastic is characterized by the content of black pigment particles and aluminum particles from reflector surfaces. They result in a smooth, shiny, black surface, which is usually welcome for technical reuse.

Characteristic property values for the molding composition according to the invention are Vicat softening temperature 106 ° C Tensile strength according to DIN 53 455 53.5 MPa Elongation at break according to DIN 53 455 3.4% E-module according to DIN 53 455 3112 MPa Impact strength according to Charpy (ISO 179) 9.13 kJ / m ² Notched impact strength according to Izod (ISO 180) 2.02 kJ / m ² Melt viscosity at 220 ^o C, 5 MPa 1163 Pa s Melt index MFI 230 ^o C / 3.8 3.58 g / 10 min reduced viscosity in chloroform 52.0 ml / g Gloss according to DIN 67 530 at 20/30/85 ^o 60.0 / 83.1 / 96.8 Composition PMMA / ABS / PC: 57 / 29-35 / 4 - 10% The impact strength can be improved by adding ABS molding compounds. Additions of 5 to 25% by weight significantly increase the impact strength, as can be seen from the following table: without impact modifier 9.1 kJ / m ² 5% impact modifier 10.5 kJ / m ² 10% impact modifier 10.8 kJ / m ² 15% impact modifier 12.8 kJ / m ²

Recycled materials can also be used as impact modifiers Material from production waste or from single varieties used molded parts are used.

The removal of infusible particles from the pre-cleaned regrind is basically in the way possible that the ground material in an organic solvent, such as acetone or chloroform, the solution is filtered and the solvent is evaporated. This way of working is little economically. Surprisingly, one for the technical reusability by adequate cleaning Melt filtration can be achieved. This measure proves turns out to be economical if the pore size of the filter is like this is chosen on the one hand the particles that are decisive contribute to the deterioration of properties, are removed, but on the other hand high losses due to removal of particle-rich material can be avoided. It was found that this goal with pore sizes of 0.1 to 0.2 mm is achieved. With pore sizes of up to 0.1 mm, the Filtration pressure steep due to clogging of the filter pores on. However, the filtration of finer particles can be carried out a filter cascade with gradually decreasing Pore size, for example up to 0.04 mm, master. At Pore sizes over 0.2 mm approximate the property values those of the unfiltered material. Also with problems with narrow tool channels. Best has a pore size of about 0.2 mm has proven itself because it is good Material properties, low material losses or low filter consumption and good Processing properties guaranteed. For the technical implementation of melt filtration continuous filters are suitable (cf. D. Brünger, "Plastics" Volume 82, 1992, pp.971-973). They mostly contain rotating rotating protruding into the melt stream Filter discs. This causes particles to be loaded Filter surfaces led out of the melt stream and fresh filter surfaces introduced. The loaded ones Filter surfaces can either be replaced or with a Side flow of the filtered material in the counterflow direction be cleaned continuously. The particle-rich outflow is discarded. Such filtration systems are expediently installed in an extrusion machine on which the pre-cleaned regrind mixed homogeneously and into one uniform molding compound granules extruded and broken becomes. Impact modifiers, lubricants, Stabilizers against the oxidative degradation of minerals Polymer and other common additives can be incorporated.

The prepared granulated molding compound can be prepared in the usual way Injection molding machines processed into high quality molded parts become. The processing properties correspond largely those of PMMA molding compounds. The production of opaque parts of motor vehicle rear and Direction indicators, especially the lamp housing, is a preferred area of application, because of that Recycling cycle is almost closed. The achievable surface quality is usually sufficient to reflect reflections by vapor deposition of aluminum. The moldings are with usual PMMA molding compounds for the light-conducting parts compatible and can be used in a conventional manner welded, glued or screwed.

Claims (8)

1. Thermoplastic plastics moulding composition made up as follows:

   50 - 65 wt.-% of polymethyl methacrylate or copolymer of methyl methacrylate with 1 to 20 wt.-% of ethylenically unsaturated, radically polymerisable monomers which are copolymerisable therewith,

   25 - 40 wt.-% of impact resistant plastics based on acrylonitrile, butadiene and styrene,

   1 - 20 wt.-% of polycarbonate plastics, and

   having a Vicat softening temperature of at least 102°C, a tensile strength of at least 50 MPa and an elongation at break of at least 3%, the proportion of particulate ingredients which do not melt at 250°C being less than 5 wt.-%, characterised in that the thermoplastic plastics material consists predominantly or entirely of recycled car rear lights and indicators and is free from ingredients which do not melt at up to 250°C measuring more than 0.2 mm (screening size).
2. Thermoplastic plastics moulding composition according to claim 1, characterised in that it is free from ingredients which cannot be melted up to 250°C measuring more than 0.04 mm (screening size).
3. Plastics moulding composition according to claim 1, characterised in that it consists of 5 to 50 wt.-% of new or recycled ABS plastics.
4. Injection moulded plastics moulding consisting of a plastics moulding composition according to one of claims 1 and 3.
5. Car rear or indicator light housing, characterised in that it consists of a thermoplastic plastics material according to one of claims 1 and 3.
6. Car rear or indicator light housing according to claim 5, characterised in that it is attached to a transparent cover made of PMMA.
7. Method of producing the plastics moulding composition according to one of claims 1 and 3, characterised in that a ground material from recycled vehicle rear and indicator lights, substantially free from metal parts and specifically heavier material particles, is melted and the melt is filtered through a screen with a mesh size of not more than 0.2 mm.
8. Method according to claim 7, characterised in that the melt is filtered through a screen with a mesh size of at least 0.1 mm.